Spoiler
 

Does the Toyota Yaris stock spoiler help or hinder aerodynamics?

Can you post a photo? I Googled the Yaris and if its the small subtle moulded spoiler with only a small deflection angle then I don't think it would increase drag very much, it is good for the air to leave the back of the car in a clean break at as close to horizontal as possible as it prevents it from wrapping round and causing lift (which is drag on a car) and allows it to flow smoothly for a bit longer after the car before becoming turbulent. If it can easily be removed then you could try some A-B-A testing. I think you would notice a small decrease in drag and rear stability but it wouldn't be drastic I don't think.

Do you mean this OE rear spoiler?
https://www.toyota.com/images/vehicle...spoiler_lg.jpg

And viewed from the rear:
https://www.factorywings.com/catalog/1835AYARIS2FS.jpg

I also found this aftermarket one:
https://www.customautotrim.com/spoilers/?a=img&id=2791

Presumably the same spoiler as above, from this angle it appears to be an anti-lift design:
https://www.customautotrim.com/bodyki...yaris-wing.jpg

And this is a nice, unobtrusive design for the Yaris sedan:
https://www.customautotrim.com/spoilers/?a=img&id=2992

And I also found several custom-fit wing designs for the Yaris sedan, but I didn't bother to post them since we all know they're drag monsters.
But as far as the hatchback goes, I'll chalk it up as yet another OE 'positive downforce' design on a two-box...seems to be a trend, hmmmmmmm.;)

lol those useles spoilers are all for looks. i dont see the point of paying $500-$1000 for a chunk of plastic on my roof/trunk.

A spoiler/wing is useless for actually creating downforce I think unless there are side walls on it, or else the air just slips off the sides. I was just wondering in terms of drag. And yes, I had that OEM hatchback spoiler in mind. Thanks :)

Not all the air, only at the very edges, the air will travel on a sort of path of least resistance so it is much easier for the air in the centre on the car to get deflected up slightly then all the way around to the side, it looks like a pretty subtle angle too so I wouldn't worry about it too much. I don't think I've ever seen a spoiler with a sidewall unless it was also supporting a suspended wing. One way to think of it is slightly more down force means you can take corners at slightly higher speeds which means less braking and acceleration (fuel). But again we are not talking in very noticeable changes I don't think.

Actually, those Yaris spoilers are less than $200 painted...not a bad deal imo.

if you like the looks of that thing, sure, i'm not sure what aftermarket spoilers go...and it will fit the car perfectly.

but if you want to get something for 200$ that will save gass... you could look at grillblocks, smooth bubcaps, underbody fairings, or delete the radio antenna and replace it with an interior one... or just use the 200$ on gas...or see if there are any other items on the option list that could save gas...

the only spoilers that are somewhat effective are the ones that prevent the airflow from going where you don't want it... mostely this has to do with bad car body design to begin with, like the beetle article on autospeed demonstrates for example.

the stock yaris has a 0.29 drag coefficient however... there's few cars that do better these days...

yea if ya liek it its your car and money so do what you want but if it were me id rather just save the $200, wait a year or 2 then take one off a car at a junkyard for $10:D its what ive done with my 95 truck, adding options that werent on it to begin with(i added cruise control for $10, fancy multi cigarette lighter kickpannel for $5, bucket seats with center console for less than $100)

ok rear spoilers on a FWD car are useless and all for looks:p

I agree with you to a point but I find your statement kinda broad...there's no Uncle Ben's instant r.i.c.e.:thumbdown: factor here because we're not talking about a 3ft high, double-decker DTM pedestal wing.
I've mentioned this in these forums before, but I'll pose this question to you...how do you explain the use of OE rear spoilers used exclusively on high FE, FWD vehicles?(eg:Honda Civic Hybrid, VW Jetta TDI, ect.)

Home depot vinil moulding
 

This kind of spoiler might be easy and cheap done by using Home Depot vinil mouldning for about $2.

I'm sorry i'm not sure if you are buying one or considering removing the one you already have. I would say if its already on it would make a minor difference of you took it off so don't worry about it (if you do then try some A-B-A testing to see what kind of difference it made), but i wouldn't pay money to get one, if you want down force I would go with a belly pan (perhaps with a built in splitter?) which increases front end down force slightly so less understeer while improving overall Cd.

I cant believe how everybody here points blame at oem spoilers for adding drag.

You people act like if its an oem spoiler, no matter what car or what kind of spoiler, it must just be another tacky add-on for looks.

Sure there are some cars out there where that may be true. But certainly not all. You guys really think any reputable car company just throws on any spoiler that the designers come up with? Cmon guys.

Some cars even have stated facts for optional "aero packages". This info can be found in the cars' brochere, such cars like some Saabs, lexus, and infinity. Heres a quote from infinity in fact:

Comprehensive airflow management, with underbody sculpting, for low 0.29 coefficient of drag (Cd) and zero-lift front aerodynamics (0.28 Cd and zero-lift front and rear with optional Aero Package)

The aero package includes a rear spoiler shown here:
https://images.automotive.com/stock/3...AN%20MODEL.JPG

Heres a quote from Honda about the spoiler on the civic:
The Civic Hybrid and Civic Coupe models use a lip spoiler on the trunk that cleans up the airflow behind the vehicle and it creates downforce at high speeds.

The fact is many oem spoilers actually reduce drag. On many 3 box sedans small lip spoilers and low-rise spoilers help the air coming over the back window reattach and straighten out. On wagons and hatches like the yaris, a spoiler like the oem yaris one, prevents the air from following the downward curvature of the back glass and keeps its going nice and straight past the vehicle.

this is a good read
https://www.autospeed.com/cms/A_1634/article.html

it shows that a clean cut trailing edge is rather important to reduce drag this is why some cars have a small straight "spoiler" at the rear of the roofline.

on the other hand most real spoilers that generate downforce also generate drag...on a car that has enough power to send it into the air, you might want to invest some of that power to keep it on the road.


a while ago i came across an article that showed that ,at least over here, the yaris is mainly bought by elderly people ... not exacly sexy... you don't want the granny image stamped on a smooth compact car, that wants to be young and trendy yet affordable and practical... so how do you underline that you didn't design the car to be driven by people who do half the speedlimit all the time...get some "sporty options".
(btw if i where to get a new car right now i'd sure make a testdrive in the yaris... it looks great with or without the spoiler)

i don't mean to say it's impossible there's some advantages to that spoiler... just that untill i see figures that prove the spoiler actually improves FE there's a chance that it's more for image than anything else.

even a carmaker with a rather green image like toyota knows that a cool car still sells better then an efficient one